The present invention relates to the general field of solid fuel combustion methods and devices and is more particularly concerned with a wood log combustion method and supporting device therefor.
Solid fuel burning stoves such as wood-burning stoves which rely on radiation and convection of the stove itself are well known. In view of the continually increasing cost for running more sophisticated centralized heating systems relying on oil or electricity and in the context of social trends such as so-called xe2x80x9ccocooningxe2x80x9d, such stoves are becoming more in vogue. They are increasingly being used to heat various rooms in houses in lieu of or supplemental to other heating methods.
Generally, such stoves include a combustion chamber into which air is directed, burned and exited through a flue outlet generally positioned centrally at the top of the combustion chamber. The stoves are typically made of metal and bricks and burn solid combustible material such as wood, coal or the like in order to raise the temperature of the metal and bricks sufficiently to radiate and convect heat throughout the room where the stove is employed.
Typically, a door is provided on the front of the stove allowing access for adding fuel and removing ashes or other debris once the fuel has been burned. In addition, the door usually has apertures extending therethrough for enhancing radiation from the stove and for creating a draft. The draft provides air containing oxygen to ignite the fuel and maintain combustion within the stove.
It has long been recognized that wood, particularly well seasoned, dry hardwood contains a very substantial potential of thermal energy that can be released by burning. Among the various problems that have been encountered in the use of wood in stoves and furnaces as a thermal energy source is the fact that the wood tends to burn rapidly with the consequent release of more thermal energy than that which can be effectively heat-exchanged into a distribution medium such as air. Accordingly, a substantial portion of the potential energy of the fuel is lost through the exhaust stack, flue or chimney.
Various techniques have been used in attempts to overcome or at least reduce problems associated with poor heating efficiency related to loss of heat through the exhaust stack or flue. One such technique which has been utilized is that of using so-called xe2x80x9cstarved airxe2x80x9d combustion. This technique involves the restriction of the amount of air and thus oxygen available in the combustion chamber so as to slow the rate at which the wood burns. Various designs of stoves commonly referred to as slow combustion stoves have been designed to achieve xe2x80x9cstarved airxe2x80x9d combustion.
Although these xe2x80x9cstarved airxe2x80x9d combustion techniques have produced some degree of success, they nevertheless have also created additional problems. Indeed, the use of so-called xe2x80x9cstarved airxe2x80x9d combustion results in incomplete combustion of many of the volatile hydrocarbon constituents of the wood. Collectively, these constituents when they become deposited are referred to as creosote. Hence, creosote is a complex of aromatic hydrocarbons including tar acids, tar bases and phenols.
Many of these constituents become deposited on the surfaces through which the flue gasses pass if the flue gas temperature drops below a given temperature. These deposits, in turn, build up and tend to clog and thus interfere with the movement of gasses through the flue. Also, being flammable, creosote has a tendency to catch fire resulting in so-called chimney fires bringing with it potential serious material as well as human consequences.
Furthermore, the use of slow combustion stoves results in a lower heating efficiency inasmuch as all the solid fuel available is not burned within the combustion chamber. Also, it is well know that too little air, preventing complete fuel combustion, leaves a lot of ashes in the stove. Furthermore, incomplete combustion also produces carbon monoxide which is a toxic gas.
On the other hand, it is also well known in the furnace or fireplace art that too much air causes rapid combustion and a great loss of heat through the fireplace or stove pipe/chimney. Potentially recoverable energy is lost and the combustible material soon is exhausted. Temperature spikes, wherein the temperature rises to relatively high levels in a relatively short lapse of time are sometimes created leading to discomfort and to potential damage to the heating components.
Hence, the lack of control over the rate of combustion of the combustible material in both open and restricted air environments leads to various serious drawbacks such as loss of energy, poor heating efficiency, wastage of fuel with ecological repercussions, discomfort and potential danger for both material goods and human life. Accordingly, it would prove to be highly desirable to provide both a method and a device for facilitating the control of the rate of combustion of combustible material.
When solid combustible materials such as wood logs, coal or the like are burned or combusted in a open air environment such as a fireplace or in a xe2x80x9cstarved airxe2x80x9d environment such as a slow combustion stove, the solid combustible material is often supported in an elevated or spaced relationship relative to the base wall of the fireplace or stove. Known supporting arrangements for wood logs include log holding throughs, andirons, log retaining grates and the like.
These supporting arrangements are commonly used to elevate the wood logs in order to allow needed oxygen to circulate around the logs, particularly underneath and around their sides and backs so as to facilitate the combustion. Conventional supporting arrangements are also typically provided with spaces or apertures formed therein for allowing ashes to fall through and be separated from the unburned wood. Some supporting arrangements also allow the fireplace or stove to be cleaned. and facilitate the removal of the ashes without having to remove the supporting arrangement itself and/or the logs mounted thereon.
Although conventional log supporting arrangements provide numerous advantages, they nevertheless suffer from at least one major drawback in that they have not been designed to maintain the logs in a predetermined pattern for improving the heating efficiency and obliviating or reducing the herein above-mentioned drawbacks associated with both xe2x80x9copen airxe2x80x9d and xe2x80x9cstarved airxe2x80x9d environments. Accordingly, there exists a need for an improved log burning method and associated log holding structure therefore.
It is therefore an object of the present invention to provide an improved log supporting device for an improved log combustion method.
Advantages of the present invention include the proposed method and structure allowing for efficient regulation of the rate of combustion of combustible material in a combustion chamber. Also, the present invention provides enhanced combustion and heat transfer efficiency.
Furthermore, the proposed invention allows for the heat output of the combustion chamber to be maintained substantially constant, in particular preventing over-temperature conditions within the combustion chamber.
Still further, the proposed invention may potentially allow for the reduction in the amount of creosote, carbon monoxide and other potentially harmful combustion by-products. Also, the proposed invention potentially allows for safer, more economical and ecological usage of solid combustible material.
Still furthermore, the proposed supporting structure is designed so as to be manufacturable using conventional forms of manufacture and conventional material so as to provide a log supporting structure that will be economically feasible, long-lasting and relatively trouble-free in operation.
According to an aspect of the present invention, there is provided a log supporting structure for supporting a log positioned within a combustion chamber, the log having a generally elongated configuration defining a log longitudinal axis, a log circumferential surface, a log first end and an opposed log second end, the combustion chamber defining a chamber base wall and having a gas contained therein; the log supporting structure comprises:
a generally elongated supporting rod defining a rod longitudinal axis, a rod circumferential surface, a rod first end and an opposed rod second end, the supporting rod for supporting the log first end at a predetermined location therealong so that the log longitudinal axis extends in a generally perpendicular relationship relative to the rod lonqitudinal axis and in an angled relationship relative to and adjacent the chamber base wall with the log first end positioned above the log second end;
a spacing base extending from the supporting rod for resting on the chamber base wall and maintaining the supporting rod in a predetermined spaced relationship relative to the chamber base wall;
the spacing base having a generally flaring configuration in a geometrical plane generally perpendicular to the rod longitudinal axis and in a direction leading away from the supporting rod;
the spacing base being provided with a longitudinal venting means for allowing the gas to flow between the chamber base wall and the supporting rod in a first flow direction generally parallel to the supporting rod at least partially along the supporting rod;
the spacing base being provided with a transversal venting means for allowing the gas flowing in the first flow direction to flow in a second flow direction generally perpendicular to and away from the supporting rod at the [a] predetermined location along the supporting rod and generally parallel to the chamber base wall from the log first end toward the log second end.
Typically, the longitudinal venting means allows the gas to flow in the first flow direction from a position located adjacent the rod first end to a position located intermediate the rod first and second ends, preferably to a position located adjacent the rod second end.
Preferably, the spacing base includes at least two spacing legs, each of the spacing legs having a generally flaring configuration in a geometrical plane generally perpendicular to the rod longitudinal axis and in a direction leading away from the supporting rod; the longitudinal venting means including a venting aperture formed in at least one of the spacing legs, the transversal venting means including the legs being spaced from each other along the supporting rod so as to define a leg spacing therebetween.
Preferably, at least one of the spacing legs has a generally triangular configuration defining a leg apex and a leg base, the leg apex being attached to the supporting rod.
Preferably, the venting aperture has a generally triangular configuration defining a generally triangular aperture frame, the aperture frame including a frame bridging segment extending across the leg base and a pair of frame spacing segments tapering towards each other in a direction leading from opposed ends of the frame bridging segment towards the leg apex.
Typically, at least one of the spacing legs is provided with at least one resting prong extending therefrom, the resting prong defining a prong abutment surface for abuttingly contacting the chamber base wall when the log supporting structure is resting on the chamber base wall, the resting prong defining a base wall-to-leg clearance between the chamber base wall and the spacing leg when the prong abutment surface abuttingly contacts the chamber base wall.
Typically, at least one of the spacing legs is provided with a pair of spaced apart resting prongs extending therefrom, each of the resting prongs defining a prong abutment surface for abuttingly contacting the chamber base wall when the log supporting structure is resting on the chamber base wall, the resting prongs defining a base wall-to-leg clearance between the chamber base wall and the spacing leg when the prong abutment surfaces abuttingly contacts the chamber base wall.
Preferably, the rod circumferential surface defines a generally arcuate rod-to-log contacting section. The latter extends over an angular range at least equal to 180 degrees.
Preferably, the supporting rod has a generally disc-shaped cross-sectional configuration and the leg apex defines a generally arcuate rod receiving recess for receiving a rod-to-leg contacting section of the rod circumferential surface, wherein the remainder of the rod circumferential surface defines a rod-to-log contacting section having a generally arcuate configuration.
Preferably, the supporting rod and the spacing leg are both made out of a metallic alloy, the rod-to-leg contacting section being attached to the rod receiving recess by welding.
Preferably, the spacing leg is made out of a generally flat piece of material.
According to another aspect of the present invention, there is provided in combination, a combustion chamber and a log supporting structure for supporting a log positioned within the combustion chamber, the log having a generally elongated configuration defining a log longitudinal axis, a log circumferential surface, a log first end and an opposed log second end, the combustion chamber defining a chamber base wall and a chamber peripheral wall, the combustion chamber having a gas contained therein; the log supporting structure comprises:
a log supporting means attached to the combustion chamber for supporting the log so that the log longitudinal axis extends in an angled relationship relative to the chamber base wall with the log first end positioned above the log second end; and
an attachment means for attaching the log supporting means to the combustion chamber.
Preferably, the log supporting means is positioned, configured and sized so as to support the log in a generally proximal relationship relative to the chamber base wall, the log supporting means supporting the log generally adjacent the log first end while allowing the log second end to be supported by the chamber base wall; whereby when the log is supported by the log supporting means and the chamber base wall respectively adjacent the log first and second ends, the log and the chamber base wall form a generally triangular air volume therebetween.
Typically, the attachment means allows for adjustment of the angular relationship between the log longitudinal axis and the chamber base wall and The attachment means allows for adjustment of the spacing between the log and the chamber peripheral wall.
Preferably, the log supporting means includes:
a supporting rod for supporting the log so that the log longitudinal axis extends in an angled relationship relative to the chamber base wall with the log first end positioned above the log second end, the supporting rod defining a rod longitudinal axis; and
a supporting bracket attached to the chamber peripheral wall and supporting the supporting rod perpendicularly to the rod axis in a predetermined spaced relationship relative to the chamber base wall.
Preferably, the supporting bracket is of a generally L-shaped configuration and defines a bracket attachment leg and a generally perpendicularly extending bracket supporting leg, the latter supporting the supporting rod in a predetermined lateral spaced relationship relative to the chamber peripheral wall; and wherein the attachment means includes:
a chamber attachment aperture formed in the chamber peripheral wall;
a bracket attachment aperture extending through the bracket attachment leg; and
an attachment component for extending through both the chamber attachment aperture and the bracket attachment aperture.
Preferably, the bracket supporting leg is provided with retaining notches formed therealong for restricting lateral movement of the supporting rod along the bracket supporting leg and for allowing adjustment of the predetermined lateral spaced relationship between the supporting rod and the chamber peripheral wall;
the bracket attachment leg being provided with a set of spaced apart chamber attachment apertures for allowing adjustment of the predetermined spaced relationship between the supporting rod and the chamber base wall.
According to a further aspect of the present invention, there is provided a method for combusting a wood log inside a combustion chamber, the combustion chamber having an air inlet, an air outlet; the wood log having a generally elongated configuration defining a log longitudinal axis, a log first end, a log second end, a log length, a log diameter and a log circumferential surface, the method comprises the steps of:
positioning the log within the combustion chamber generally adjacent the chamber base wall in a combustion configuration wherein the log first end is at a first spacing distance relative to the chamber base wall and wherein the log second end is at a second spacing distance relative to the chamber base wall, the first spacing distance being greater than the second spacing distance so that the log longitudinal axis is generally angled relative to and adjacent the chamber base wall and so that the log and the chamber base wall define a generally triangular air volume therebetween;
ensuring that the air volume between the log and said chamber base wall allows circulation of air generally thereacross in both a first direction generally perpendicular to the log longitudinal axis adjacent the log first end and a second direction generally parallel to the chamber base wall from the log first end toward the log second end;
igniting the log; and
maintaining the log in the combustion configuration during at least part of the combustion of the log.
Preferably, the step of positioning the log within the combustion chamber generally adjacent the chamber base wall ensures that the rod longitudinal axis is angled from the chamber base wall by an angle of about fifteen (15) degrees.
Preferably, the method further comprises the step of adjusting the angular relationship between the rod longitudinal axis and the chamber base wall so as to modulate the combustion speed.
Preferably, the angular relationship between the rod longitudinal axis and the chamber base wall is further adjusted so as to maintain a flame burning substantially along and across the log.